The invention relates to an apparatus on a spinning preparation machine, for example, a flat card, roller card, draw frame or the like, for monitoring fibre material, having at least one rotating roller that delivers fibre material.
Unacceptable and undesirable piling up of material in textile machines, especially flat cards, roller cards or draw frames, can cause damage in practical operation. In the textile machinery sector, particularly in the case of flat cards and roller cards, dependent on the system the material to be processed is transferred between rotating rollers, which are mostly also fitted with clothings. Thus, for example, the fibre material is transferred from the feed to the licker-in, from the licker-in to the cylinder, from the cylinder to the doffer etc. The fibre material to be transferred, for example, cotton fibres, usually consists of a relatively thin fibre mat or fibre fleece. For this and also for other technological reasons, the paths provided for the fibre material are relatively narrow. Particularly at the transfer points, it may happen that the fibres are not passed on properly and material piles up undesirably. In these regions, problems may also arise as a result of clinging fibres, unsatisfactory suction extraction, or the like. All these malfunctions result mostly in serious problems in the machine. The risk of serious damage to individual machine elements is high whenever there is an unduly large amount of fibre material on the rollers or at the transfer points. This can ultimately lead to the cracking of covers, fixings, roller bearings, guide elements etc.
With a known apparatus (DE 32 20 636 A) on a flat card, downstream of a pair of take-off rollers there is arranged a fibre guide plate pivotable about an axis parallel to the take-off roller nip. In its working position, the fibre guide plate lies against a limit switch for stopping the machine; the limit switch is depressed. When disruptions occur during sliver formation, e.g. tearing of the sliver, fibre builds up in the region of the fibre guide plate, this is pivoted out of the vicinity of the limit switch, leading to stoppage of the machine. The disadvantage here is the structural complexity. In particular it is inconvenient that the limit switch directly detects only the position of the fibre guide plate. A build-up of fibre can only be detected indirectly. Furthermore, a response is to be initiated only when a downstream disruption, such as tearing of the sliver, occurs. Finally, it is not possible to detect and monitor the magnitude of the fibre build-up using this apparatus.
It is an aim of the invention to produce an apparatus of the kind described initially that avoids or mitigates the said disadvantages and permits direct detection of undesirable accumulations of fibre material in a structurally simple manner.